Conventionally, as disclosed, for example, in Japanese patent document JP-A-2003-218996, the Bluetooth-enabled hands-free apparatus for use in a vehicle connects, according to a Bluetooth communication standard, a hands-free call through a Hands-Free Profile (HFP) to a Bluetooth-enabled cellular phone, when the cellular phone is brought into the vehicle and is in a Bluetooth communication enabled condition. Further, multiple connections of HFP are connected simultaneously to multiple cellular phones by the hands-free apparatus in recent years, according to the above patent document. That kind of connection is known as “multiple connections” of HFP.
When the multiple HFP connections are established from the hands-free apparatus to the multiple cellular phones, one of the multiple phones may receive an incoming voice call while another phone is involved in a hands-free call. The assignee of the present application has filed another application JP-A-2009-224984 (US 2009/0209297A1) that discloses a hands-free call switching scheme involving two cellular phones. In that disclosure, when one of the cellular phones (i.e., a subject phone) receives an incoming voice call with the other cellular phone that is having the hands-free call, the hands-free call of the other cellular phone is switched from a hands-free call condition to a hold condition before picking up the incoming voice call to the subject phone as a hands-free call.
Now, the hands-free call through the HFP may take the following two forms, that is, a hands-free call condition and a handset call condition. The hands-free call condition uses the speaker and the microphone on the hands-free apparatus for a conversation that is not private, and the handset call condition uses the speaker and the microphone on the cellular phone for a conversation that is private.
Thus, a problem arises from the call switching scheme in the above-described another application when, for example, one of the multiple cellular phones (i.e., the subject phone) receives an incoming voice call while the other cellular phone is involved in a handset call, because the above application does not disclose any method for handling the just-described situation. In this case, if the hands-free apparatus allows a user operation for picking up the incoming voice call to the subject phone, for example, with a restriction of the user operation for the handset call of the other phone, the handset call of the other phone is left un-attended. In other words, a proper handling method for attending both of the two calls through multiple HFP connections, that is, the incoming voice call to one cellular phone and the handset call to the other cellular phone has been expected.